In known vehicles of this type, for example the "CLIO" marque vehicle manufactured by RENAULT, the first finger is covered by a mass of solid rubber and is engaged in an opening of the support arm with which it co-operates by coming into abutment to limit displacement of the power unit, at least parallel to the second axis.
That known embodiment operates in satisfactory manner but suffers from the drawback that when the first finger is in abutment against the wall of the opening in the support arm, a large amount of friction is generated between the finger and the wall which impedes operation of the antivibration support in the vertical direction.
In particular, this friction tends to transmit vibratory motion directly between the power unit and the vehicle structure of the vehicle, even though the antivibration support is specifically provided to minimize such transmission as much as possible.